mypy

gh-127443: add tool for linting `Doc/data/refcounts.dat` #10948

Job	Run time
Run mypy on Lib/_pyrepl	27s
Run mypy on Lib/test/libregrtest	24s
Run mypy on Tools/build	25s
Run mypy on Tools/cases_generator	22s
Run mypy on Tools/clinic	23s
Run mypy on Tools/jit	22s
Run mypy on Tools/refcounts	24s
Run mypy on Tools/peg_generator	25s
Run mypy on Tools/wasm	24s
	3m 36s

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